Wire support for a vitreous longitudinal rod in a fluorescent lamp



Au 18 1964 L. NICOLARO 3,145,320

WIRE SUPPORT FOR A VITREOUS LONGITUDINAL ROD IN A FLUORESCENT LAMP Filed Feb. 16, 1962 E MHWM uwk l l s:

INVENTOR.

LOUIS NlCOLA-RO. BY

United States Patent 3,145,320 WIRE SUPPORT FOR A VITREOUS LONGITUDI- NAL ROD IN A FLUORESCENT LAMP LouisL. Nicolaro, Roselantl, N.J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 16, 1962, Ser. No. 173,660 Claims. (Cl. 313-286) This invention relates to electric discharge devices and, more particularly,to fluorescent lamps and means for mounting an elongated member therein.

It has recently been discovered that the loading per unit length, and hence the light output, of low-pressure gaseous discharge devices such as fluorescent lamps and the like can be increased without decreasing their efliciency by mounting an elongated member within the discharge space. This provides a region Within the discharge where electrons and positive ions can recombine. The resultant loss of ions and electrons through recombination decreases the diffusion length of the discharge and increases the electron temperature which, in turn, increases the loading per unit of lamp length without producing an attendant decrease in efliciency. I

To avoid obstructing the free passage of the discharge through the lamp and producing an undesirable increase in the current density per unit of cross-sectional area, the thickness of the elongated member must be kept very small compared to its surface area. Preferably, a slender glass rod is mounted within the lamp between the electrodes and oriented so as to extend along the lamp axis and the discharge space. The rod is thus suspended in the center of the discharge and provides a recombination surface in the region where the electron and ion concentration is greatest. This arrangement produces an optimum increase in the electron temperature and in the lamp loading. An axial rod highly-loaded fluorescent lamp designed in accordance with these principles is disclosed and claimed in copending U.S. application Serial No. 112,071 of D. A. Larson and P. J. Walsh, filed May 23, 1961 and assigned to the assignee of the present invention.

The manufacture of such axial-rod fluorescent lamps has presented a problem in that it is very diflicult to mount and maintain the rod in coaxial alignment with the envelope and to prevent the rod from breaking or becoming dislocated when the lamp is subjected to mechanical impacts or vibrations. The problem is'further complicated by the fact that the rod must be suspended within the lamp in such a way that the support structure does not materially obstruct the discharge, mask large areas of the bulb wall or produce objectionable blemishes or defects in the phosphor coating.

With the foregoing in mind it is the general object of this invention to provide an electric discharge device that displays an enhanced output and can be readily and economically manufactured.

Another and more specific object is the provision of a highly-loaded fluorescent lamp that achieves its high loading by the aforementioned recombination principle and which can withstand the mechanical shocks and impacts normally encountered during handling and shipping.

Another object is the provision of means for resiliently supporting an elongatedfragile member within a tubular envelope or the like without materially reducing the crosssectional area of the envelope or masking large areas of the envelope wall.

Still another object is the provision of an assembly consisting of a fragile elongated member and attached supporting means that can be easily inserted into a tubular envelope and automatically locked in predetermined position therein.

The aforesaid objects, and others which will become apparent as the description proceeds, are achieved in accordance with this invention by supporting the elongated member within the envelope by means of resilient support loops that are attached to the member and compressively locked in place by the envelope walls. The loops preferably comprise rings of braided wire that are attached to and aligned with the elongated member. The rings are slightly larger in diameter than the envelope and are thus compressively locked in place by the envelope walls. The interaction between the support rings and the curved surface of the envelope is such that the elongated member is automatically aligned with the envelope axis and the rings are disposed in longitudinally-extending relationship with the envelope and the discharge path;

The inherent resiliency of the wire loops dampens the mechanical shocks and vibrations that would otherwise be transmitted from the envelope to the rod thereby protecting the latter from damage during handling and shipment.

A better understanding of the invention will be ob-. tained by referring to the accompanying drawing, wherein:

FIGURE 1 is an elevational view of a highly-loaded fluorescent lamp incorporating the rod-and-support assembly of this invention;

FIG. 2 isan elevational view of the rod-and-support assembly employed in the fluorescent lamp shown in FIG. 1;

FIG. 3 is an enlarged sectional view of a portion of the lamp and a supported segment of the rod;

FIG. 4 is a cross-sectional view of the lamp along the line IV-IV of FIG. 3, in the direction of the arrows;

FIG. 5 is an elevational view of one of the support rings shown in the preceding figures;

FIGS. 6 and 7 are elevational views, on a reduced scale, illustrating the initial and final stages in fabricating the support rings;

FIG. 8 is a cross-sectional view through a typical highlyloaded fluorescent lamp provided with a coaxial rod illustrating the character of the discharge in lamps employing such construction;

FIG. 9 is a fragmentary sectional view of an alternative lamp embodiment; and

FIG. 10 is an elevational view of the alternative support loop shown in FIG. 9.

While the present invention may be advantageously employed in various types of electric discharge devices, it is particularly adapted for use in conjunction with highly-loaded fluorescent lamps and it has, accordingly, been so illustrated and will be so described.

With specific reference to the drawing, in FIG. 1 there is shown a highly-loaded fluorescent lamp 10 that incorporates the rod-support assembly 19 of this invention. The lamp consists of the usual tubular light-transmitting envelope 12 that has a mount 14 and an associated electrode 15 sealed into each of its ends which are, in turn, enclosed by suitable base members 16. The envelope contains the customary charge of mercury and a suitable inert ionizable gas such as argon, neon, krypton, etc. or mixtures thereof. The inner surface of the envelope 12 is coated with a suitable UV-responsive phosphor 18 that is applied in the usual manner. 1

Suspended within the discharge space between the electrodes 15 is an elongated member such as a rod 20v of circular cross-section. The rod is fabricated from glass or a similar vitreous material that will withstand the elevated temperatures generated within the discharge. The rod is preferably also coated with a layer of phosphor 21' and is mounted in substantially coaxial alignment with the envelope. The diameter of the rod compared to that of the envelope is selected in accordance with the teachings of I 3 the'aforementioned copending US. application of D. A. Larson et al., Serial No. 112,071, to obtain the greatest reduction in the diffusion length of the discharge and increase in the lamp loading.

The Invention The present invention is directed to the problem of mounting the vitreous rod 20 in the desired position within the envelope 12 and thus constitutes an improvement Over the invention disclosed and claimed in the aforesaid copending US. application of D. A. Larson et al. Briefly stated, the present invention solves this problem by means of specially designed support loops that automatically and resiliently suspend and lock the rod in the desired location within the discharge space.

As shown in FIGS. 1 and 2, and more particularly in FIGS. 3 to 5, the support loops preferably consist of rings 22 that are fastened to the rod at predetermined intervals. The support rings are preferentially fabricated from braided Nichrome wire or similar filamentary material that is relatively still: but resilient and that will withstand the elevated temperatures that prevail within the discharge Nichrome wire is well known and is fabricated from a nickel-base alloy containing from 11% to 22% chromium. It is used extensively in electrical-resistance heating elements because of its high resistivity and its ability to withstand high temperature without becoming oxidized.

The diameter D of the support rings 22 (FIG. 5) is considerably larger than the inside diameter D (see FIG. 3) of the envelope 12.

The preferred method of fabricating the support rings 22 is illustrated in FIGS. 6 and 7. A piece of wire 21 slightly longer than twice the circumference of the ring is first looselycoiled to form a ring of the proper size so that the ends of the wire overlap, as shown in FIG. 6. The wire strands are'thenintertwined to form a resilient braided-wire ring 22 of the type illustrated in FIG. 7. The free ends of the wire are subsequently wrapped tightly around both strands and the latter are separated at two preselected points toprovide a pair of openings 23 and form the finished ring shown in FIG. 5. In this particular case, the openings are located diametrically opposite one another, as illustrated. The openings are also made slightly smaller than the diameter of the rod 26 so that'when the rod is threaded through the openings it will be firmly gripped by the wire strands and securely fastened to the ring.

Assembly The assembly of the rod 20 with the support rings 22 is very readily accomplished by forcibly threading the rod through the openings 23 in the rings. The latter are then positioned substantially equal distances from each other along the rod to form an integral rod-and-support assembly 19 of the type shown in FIG. 2. The support rings are thus frictionally locked in planes that pass through the rodand are thus aligned with and extend in the same .direction as the rod axis.

The resulting assembly 19 is then inserted into the uncoated envelope 12 and located therein so that the ends of the rod are located approximately equal distances from the ends of the envelope (see FIG. 1). Since the span or diameter D of the support ring normally is larger than the inside diameter D of the envelope,the rings engage and are compressed by diametrically-opposed portions of the envelope wall into generally elliptical shape, as shown inFIGS. 1 and 3. The rod-andsupport assembly 19 is, accordingly, securely locked within the envelope 12 solely by the compression of the braided rings 22 by the envelope walls.

As will be noted most particularly in FIGS. 3 and 4, the interaction between the concave inner surface of the envelope and the compressed support rings is such that the rings are automatically positioned in planes that are aligned with and extend along the envelope axis. The rings are accordingly also aligned with the discharge path and as a result do not materially obstruct or impede the free passage of the discharge through the envelope. Since the rod intersects and is fastened to each of the rings at diametrically opposite points and the rings engage diametrically opposite portions of the envelope, the rod is also automatically positioned in substantially coaxial relationship with the envelope. In addition, the orientation of the support rings and envelope walls is such that there is essentially only point contact between them.

After the rod-and-support assembly 19 has been compressively locked in the proper position within the envelope 12, a liquid suspension of phosphor coating material is flushed through the envelope and the latter is then drained, lehred and processed into a finished lamp in accordance with standard lamp-making practice. Mounting the rod inside the uncoated envelope in accordance with the present invention accordingly permits the rod and supports ringsto be coated with phosphor along with the inner surface of the envelope during the regular sequence of operations required to fabricate the lamp.

The effect produced on the discharge of a typical fluorescent lamp L by a coaxial rod R is shown in FIG. 8. Due to the presence of the rod the region of maximum arc intensity A is shifted outwardly from the center toward the walls of the envelope .E and assumes the form of a concentric cylinder. This decreases the diffusion length of the discharge and increases the lamp loading in accordance with the principles set forth in the copending application of D. A. Larson et al. previously referred to.

mately 2% inches in diameter and spaced about one foot apart. The rod diameter in this instance was about /8 inch and the diameter of the wire from which the rings were formed was about 0.025". The openings between the strands through which the rod was threaded were approximately 7 inch at their widest point.

Alternative. Embodiment The support loops obviously do not have to be of circular configuration but can be semi-circular or U- shaped. In FIG. 9 there is shown a lamp 10a that contains an assembly 19a having a rod 20a that is held in substantially coaxial alignment with the envelope 12a by means of a plurality of U-shaped support loops 24. The loops are fabricated from braided wire in the same manner as the rings described previously and are each provided with an aperture 25 located approximately at the center of the loop, as shown most particularly in FIG. 10.

The same compressive interlocking of the rod-andsupport assembly 19a is obtained in this embodiment by making the normal span of the loops 24 (dimension X in FIG. 10), that is, the distance between the ends of the loop when the latter is in relaxed condition, considerably greater than the inside diameter D (see FIG. 9) of the envelope. Upon insertion of the assembly into the lamp envelope the ends of the loops engage and are compressed by diametrically opposite portions of the envelope thus forcing the ends inwardly toward each other and distorting the loops into more or less semicircular configuration, as shownin FIG. 9. The coaction between the ends of the loop and concave inner surface of the envelope once again is such that the loops are automatically disposed in planes that are aligned with the rod axis and the discharge path and the rod is positioned in coaxial relationship with the envelope.

It will be appreciated from the foregoing that the objects of the invention have been attained insofar as means have been provided for accurately positioning and supporting an elongated member, such as a rod, within the discharge space of electric discharge device without materially impeding or obstructing the passage of the discharge. Moreover, the support members are such that they can be very readily and economically fabricated and assembled with the rod and envelope, and coact with the latter in a manner such that the rod is resiliently locked in place and thus protected from damage by mechanical shock and vibration.

While several embodiments have been illustrated and described in detail, various modifications in the construction and arrangement of parts can be made without departing from the spirit and scope of this invention.

1 claim as my invention:

1. In an electric discharge device having a tubular envelope that contains a pair of spaced electrodes, the combination of an elongated member that extends longitudinally of said envelope and the discharge space between said electrodes, and means supporting said elon gated member in a predetermined region of the discharge space remote from the walls of said envelope, said supporting means comprising a plurality of resilient wire loops compressively locked by said envelope at preselected intervals along the discharge path, each of said loops being substantially aligned with and extending in the same direction as the axis of said envelope, said elongated member being fastened to said loops at points thereon located in the aforesaid predetermined region of the discharge space.

2. In an electric discharge device comprising a tubular radiation-transmitting envelope containing an ionizable medium and having an electrode located proximate each of its ends, the combination of a rod-like member that extends longitudinally of said envelope and the discharge space between said electrodes, and means supporting said member in a predetermined region of the discharge space remote from the Walls of said envelope, said supporting means comprising a plurality of relatively stiff but resilient wire loops that are disposed within said envelope at intervals along the discharge path and have a span normally greater than the inside diameter of said envelope, each of said loops being located in a plane that is in substantial alignment with the axis of said envelope and being locked in such position solely by the compressive force exerted thereon by the engaged portions of the envelope walls, said elongated member being fastened to said loops at points thereon that lie within the aforesaid predetermined region of the discharge space.

3. In a fluorescent lamp having a light-transmitting tubular envelope that contains an ionizable medium and a pair of spaced electrodes located proximate its ends; the combination of a rod that extends longitudinally of said envelope and for a considerable distance along the discharge space between said electrodes; and means supporting said rod in a predetermined region of the discharge space proximate the axis of said envelope; said supporting means comprising a plurality of relatively stiff but resilient wire loops disposed within said envelope and spaced at intervals along the discharge path; each of said loops normally having a span greater than the inside diameter of said envelope and being located in a plane that is substantially aligned with the axis of said envelope, whereby said loops engage and are compressively distorted by oppositely disposed portions of said envelope and are locked therein solely by means of such compression; said rod being fastened to said loops at points thereon that lie within the aforesaid predetermined region of the discharge space.

4. The combination in a fluorescent lamp of a rod and support loops as set forth in claim 3 wherein said rod is fabricated from vitreous material and is supported in substantially coaxial relationship with said envelope by said support loops, and said rod and loops are coated with fluorescent material that is responsive to radiations generated by the electric discharge.

5. An assembly adapted for insertion into the tubular envelope of an electric discharge device comprising, in combination, a rod-like member, and a plurality of resilient wire support loops that are fastened to said member at predetermined intervals and are each disposed in a plane that is substantially aligned with said member.

6. The assembly set forth in claim 5 wherein, said support loops constitute closed rings, and said rod-like member intersects and is fastened to each of said rings at two points.

7. The assembly set forth in claim 5, wherein, said support loops are U-shaped, and said rod-like member intersects and is fastened to an intermediate portion of each of said loops.

8. A support for suspending an elongated member within a tubular envelope or the like comprising a resilient loop of braided wire provided with an opening in the wire strands dimensioned to receive and frictionally engage a part of said elongated member.

9. A support as set forth in claim 8 wherein, said loop comprises a closed ring, and two openings are provided between the braided wire strands for fastening the ring to the elongated member at two widely separated points.

10. In an electric discharge lamp having a tubular envelope that contains a pair of spaced electrodes, the combination of an elongated member that extends along the discharge space between said electrodes, and means suspending said member in a predetermined region of the discharge space remote from the walls of said envelope and from said electrodes, said suspension means comprising a plurality of resilient loop members that are attached to said elongated member and are compressively locked by diametrically-opposed portions of the envelope in planes that pass through and are aligned with the axis of said envelope.

McNeill June 1, 1909 Lemmers Nov. 21, 1944 

10. IN AN ELECTRIC DISCHARGE LAMP HAVING A TUBULAR ENVELOPE THAT CONTAINS A PAIR OF SPACED ELECTRODES, THE COMBINATION OF AN ELONGATED MEMEBR THAT EXTNED ALONG THE DISCHARGE SPACE BETWEEN SAID ELECTRODES, AND MEANS SUSPENDING SAID MEMBER IN A PREDETERMINED REGION OF THE DISCHARGE SPACE REMOTE FROM WALLS OF SAID ENVELOPE AND FROM SAID ELECTRODES, SAID SUSPENSION MEANS COMPRISING A PLURALITY OF RESILIENT LOOP MEMBERS THAT ARE ATTACHED TO SAID ELONGATED MEMBER AND ARE COMPRESSIVELY LOCKED BY DIAMETRICALLY-OPPOSED PORTIONS OF THE ENVELOPE IN PLANES THAT PASS THROUGH AND ARE ALIGNED WITH THE AXIS OF SAID ENVELOPE. 